Antimicrobial and antitrypanosomal activities of methanol root extract and fractions of Brenania brieyi (De Wild) Petit (Rubiaceae)

Abstract

Brenania brieyi (Rubiaceae) is used in ethnomedicine for the treatment of malaria, microbial infections, trypanosomal disease, infertility and inflammatory disorders. The study determined antitrypanosomal and antimicrobial activities of extract and fractions of B. brieyi. Cold maceration and solvent-solvent partitioning were used to obtain the extract and respective fractions in order of their increasing polarity: n-hexane, dichloromethane, ethylacetate and absolute methanol. Phytochemical analysis, acute toxicity test and haematological parameters (Packed Cell Volume, parasitemia count) were carried out using standard procedures. Rapid matching and Agar dilution methods were used for antitrypanosomal and antimicrobial studies respectively. The extract (100, 200 and 400 mg/kg), fractions (200 mg/kg) and diminazine aceturate (3.5 mg/kg) were administered per oral. The extract was found to be safe up to 5000 mg/kg. The phytoconstituents present in the plant include tannins, terpenoids, flavonoids, phlobatannins, alkaloids, saponins, cardiac glycosides, quinones, steroids and phenols. The methanol extract of Brenania brieyi (MEBB) root showed significant (p < 0.05) dose-dependent inhibition of parasitemia. Antitrypanosomal activity of the fractions showed that the fractions possess varying degree of parasitemia clearance at 200 mg/kg dose. Methanol fraction produced the highest parasitemia clearance (6.98 ± 0.08 %), followed by n-hexane (7.13± 0.23 %), dichloromethane (7.43± 0.14 %) while ethylacetate fraction (9.00± 0.00 %) caused the least parasitemia clearance when compared with the positive control (0.00± 0.00 %). Haematological parameters and survival time were significantly (p < 0.05) increased, n-hexane fraction exhibited significant (p < 0.05) increase in survival time at 200 mg/kg (after 26 days). Methanol fraction at MICs of 7 to10 mg/ml showed inhibitory activity against Bacillus subtilis, Salmonella typhi, Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, Streptococcus mutant, Candida albicans and Aspergillus niger. The results obtained revealed that the extract and fractions possess antitrypanosomal and antimicrobial activity. The study provides scientific evidences for the traditional uses of the plant in treating infectious diseases..